Oman Journal of Ophthalmology

ORIGINAL ARTICLE
Year
: 2012  |  Volume : 5  |  Issue : 1  |  Page : 10--15

Initial experience with Descemet stripping automated endothelial keratoplasty in Saudi Arabia


Mohamed M Hantera1, Fady El Sayyed1, Khalid M Al Arfaj2,  
1 Department of Cornea and Refractive Surgery, Magrabi Eye and Ear Center, Dammam, Saudi Arabia
2 Department of Ophthalmology, Dammam University, Saudi Arabia

Correspondence Address:
Mohamed M Hantera
Department of Cornea and Refractive Surgery, Magrabi Eye and Ear Center 31441, Al Termithi Street, P.O. Box: 1840
Saudi Arabia

Abstract

Purpose: To analyze the visual results of Descemet stripping automated endothelial keratoplasty (DSAEK) in the first consecutive 10 cases. Materials and Methods: Retrospective, non-randomized, non-comparative interventional case series. Ten eyes of 10 patients with endothelial dysfunctions of different etiology, scheduled for DSEAK, were included in this study. Indications, operative problems, and postoperative complications were noted. Best-corrected visual acuity, refractive and keratometric astigmatism, and central corneal thickness were analyzed for each patient after a minimum follow-up of 10 months. Results: In a median follow-up of 12 months (range 10-16 months), visual outcomes were satisfactory. Preoperative diagnosis included five eyes of psuedophakic bullous keratopathy and two eyes of repeated failed corneal grafts and one bullous keratopathy secondary to anterior chamber phakic IOL implantation. Two eyes with Fuchs dystrophy and cataract had combined DSAEK and phacoemulsification and IOL implantation. One patient had known glaucomatous optic nerve precluding vision better than 20/150. Of the remaining nine patients, four eyes had BSCVA of 20/40 or better by postoperative 6 months (3 by 3 months). The average pachymetry was 646.9 μm. One patient had total graft dislocation and one needed trabeculectomy. None of the patients developed graft rejection or graft failure. None of patients needed to convert to penetrating keratoplasty. Conclusion: DSAEK is safe and effective procedure in patients with endothelial dysfunctions with encouraging surgical and visual outcomes.



How to cite this article:
Hantera MM, El Sayyed F, Al Arfaj KM. Initial experience with Descemet stripping automated endothelial keratoplasty in Saudi Arabia.Oman J Ophthalmol 2012;5:10-15


How to cite this URL:
Hantera MM, El Sayyed F, Al Arfaj KM. Initial experience with Descemet stripping automated endothelial keratoplasty in Saudi Arabia. Oman J Ophthalmol [serial online] 2012 [cited 2019 Aug 26 ];5:10-15
Available from: http://www.ojoonline.org/text.asp?2012/5/1/10/94720


Full Text

 Introduction



Descemet stripping automated endothelial keratoplasty (DSAEK) is a lamellar corneal surgical technique for the selective replacement of abnormal corneal endothelium. The main indication for DSAEK is endothelial dysfunction, as found in Fuchs endothelial dystrophy and pseudophakic bullous keratopathy. [1],[2],[3] It has advantages of faster visual recovery and better visual quality secondary to less induced irregular astigmatism. Furthermore, the globe become tectonically stronger, no suture-related surface problems, better neurotrophic status, and less graft rejection or infection. It also minimizes the follow-up visits and use of corticosteroids. [4],[5],[6],[7],[8]

However, it has its own disadvantages like high endothelial cell loss (27-44% [9],[10] at 12 months) donor dislocation (10-34.7%), higher iatrogenic primary graft failure, longer operating time (45-60 min), and a steeper learning curve. [8],[11],[12]

This can explain the plenty of modifications done over the technique, e.g., enlarging incision size to be 5.00 mm instead of 3.00 mm, [9] creating stab venting incisions to evacuate any interface fluid and keep air bubble at end of procedure or not, homemade lamellar dissection or pre-cut tissues in the eye bank, lamellar dissection by mechanical microkeratome or femtosecond laser, and donor insertion, e.g., folding and pull through, injecting.

The purpose of this study was to evaluate and report the visual and surgical outcomes of this new technique of endothelial transplantation. To the best of our knowledge, such data have not been reported before in the Middle East.

 Materials and Methods



We reviewed the medical records of patients who underwent DSAEK, who completed at least 10 months of follow-up. This study adhered to the Declaration of Helsinki and was approved by the institutional review board of the clinical research.

Inclusion and exclusion criteria

The first 10 consecutive patients (age ≥18 years) who had endothelial dysfunction and had DSAEK were enrolled in the study. Patients with associated corneal stromal scarring, irregular and deformed anterior chamber (AC), vitreous in AC, aphakia, gross peripheral anterior synechiae, uncontrolled glaucoma, and gross posterior segment pathology were detected by ultrasonography B-scan. Patients' demographics and the primary indication of surgery are demonstrated in [Table 1].{Table 1}

The donor prerequisites

Healthy young donor tissue preferably below 60 years of age, endothelial count >2500 cells/mm 2 as determined by eye bank specular microscopy and scleral rim ≥2 mm all around during in situ corneoscleral button collection or preparation. A second optical quality donor cornea was always kept ready during the surgery for the initial few cases.

Surgical procedure

All 10 surgeries were performed by a single surgeon (MMH) in single tertiary care referral center from September 2008 to September 2010. In each case, surgery was performed under conventional peribulbar anesthesia. Pupillary dilation was required only in case (5) where it was combined with phacoemulsification with posterior chamber intraocular lens (PCIOL) implantation. In other cases, the pupil was constricted by instillation of three drops of 2% pilocarpine eye drops 30 min before surgery.

Donor preparation

Our surgical technique was similar to the one described elsewhere. [13] After fixing the donor button over the artificial AC (Moria, Antony, France) [Figure 1]a and according to the donor central corneal thickness (CCT) [Figure 1]b, we choose the head of mechanical microkeratome (Model CB, Moria) [Figure 1]c, which was used to create a lamellar cut in the corneal donor tissue mostly using the 350 head. After complete lamellar dissection of whole cornea, the donor tissue was transferred on a Teflon block with endothelial side up, filled up with corneal storage medium (Optisol; Chiron Ophthalmics, Irvine, CA) and covered for further trephination by Barron-Hessburg trephine (Katena Products Inc., Denville, NJ) under the surgical microscope. Preparation of appropriate size donor lenticule was created by trephination of 9.00 mm diameter.{Figure 1}

Recipient preparation

For case (8) of Fuchs dystrophy with cataract, phacoemulsification was done and PC IOL (Acrysof SA60AT; Alcon Lab Inc., Fort Worth, TX) was implanted before starting DSAEK. The pupil was then constricted with intracameral pilocarpine (0.5%) injection. The non-contact optical biometry was used to calculate power of IOL (IOLMaster; Carl Zeiss, Meditec, Germany), which was targeted to be −1.00 diopter to compensate the post DSAEK hyperopic shift which was recorded in other studies. [14] Viscoelastic material was thoroughly washed and replaced with balanced salt solution (Alcon Laboratories Inc.) using a double way cannula before starting DSAEK.

Steps of recipient preparation were also similar to that one mentioned in the literature. [7] Descemet scoring was done under air-filled AC by the modified inverted Sinskey Hook (Price Sinskey Hook; ASICO LLC, Westmont, IL) [15] which corresponded to the 9.0 mm epithelial template mark. Tan Glide prototype [Figure 1]d was used to facilitate the insertion of donor lenticule as mentioned elsewhere. [16] A diamond slit blade was used to make four equally spaced small mid-peripheral corneal incisions for drainage of additional fluid from the interface. After 10 min, complete filling of the AC with air, 40-50% of the AC air bubble was replaced with BSS. The intraocular tension was checked digitally. The conjunctiva was closed by wet field cautery. Patient received subconjunctival injection of dexamethasone and gentamycin, and one drop of atropine 1% was installed at the end of the procedure. A bandage contact lens was given in selective cases when more than two-thirds of the recipient's corneal epithelium was removed during the procedure. The eye was patched and the patient was instructed to lie supine for at least 4 to 6 hours.

The patients were discharged from the hospital after 24 hours. Postoperatively, the patients received topical moxifloxacin 0.5% four times daily; timolol maleate 0.5% twice daily; and cyclopentolate 1% twice daily for the first 10 days. In addition, they received topical prednisolone acetate 1% eight times daily for 1 week and then six times daily for the next 3 weeks. After 1 month, the dose of topical prednisolone 1% was gradually tapered over 12 months and finally discontinued. The same regimen was used in patients with DSAEK and phacoemulsification with PCIOL.

Patients' evaluation

All the 10 patients who underwent DSAEK had scheduled for 1-day, 1-week, 1-month, 3-month, 6 month, and 12-month follow-up visits. Uncorrected visual acuity, best-corrected visual acuity (BCVA), refractive and keratometric astigmatism (Pentacam corneal topography, Oculus Inc., Germany), and corneal thickness (CCT) were performed at last visit in each case. BCVA and refractive and keratometric astigmatism were tested by single trained optometrists.

The preoperative refractive errors data were obtained from spectacle history in some cases, and the IOL power was calculated from the spectacle history or from the biometry of the same or other eye. Patient 10 could not be refracted preoperatively because of severely edematous cornea.

Intraoperative and postoperative complications

Two button holes during donor preparation were occurred secondary to snatching Tenon's capsule in the revolving oscillating blade of the microkeratome. Another corneal buttons were used after ensuring perilimbal tenonectomy.

Patient (8) had total graft dislocation [Figure 2]a and b, for which the patient was readmitted at third day postoperatively and rebubbling with drainage of the interface fluid through the paracentral venting incisions, which was the reason to keep the donor in place. Patient (10) was controlled preoperatively under topical antiglaucoma medications, but angle closure glaucoma occurred secondary to occlusion of the inferior 180 degrees by the thick peripheral edge of the donor lenticule. Patient was rehospitalized, graft edge was trimmed through inferior limbal incision as well as superior trabeculectomy and mitomycin C application was done.{Figure 2}

Ten eyes of 10 consecutive patients included in this study were analyzed. The patients' demographics were demonstrated in [Table 1].

All patients had clinically significant stromal edema, microcystic epithelial edema, or frank bullous keratopathy. Pseudophakic bullous keratopathy was the main indication for DSAEK in this study. Patient (7) had iris fixated phakic IOL for correction of myopia and developed bullous keratopathy, in which DSAEK in phakic eye after phakic IOL explantation was done.

Preoperatively, in all cases, the BCVA in the affected eyes was between counting fingers (CF) to 20/50, which improved postoperatively at the last follow-up visit to be 20/50 to 20/25 (after excluding patient 10). Despite the reduced potential for correctable vision better than 20/150 in patient (10), the patient was pleased with his visual result.

Insignificant change in the keratometric astigmatism was found. Average preoperative keratometric astigmatism was 44.62 ± 1.2 (41.3 to 46.8 diopters), while in the last follow-up visit it was 44.00 ± 1.9 (42.4 to 45.3 diopters).

Average spherical equivalent error was −0.25 ± 1.55 (1.25 to −2.70) which changed to be 0.1 ± 0.87 (0.25 to −1.75) (after exclusion of patient 7 who had myopic phakic IOL explantation).

The postoperative CCT in the last visit was 646.9 ± 3.8 (699 to 540) [Table 2] and [Figure 2]c and d.{Table 2}

Case (2) with Fuchs dystrophy showed smooth interface with meniscus-shaped graft, which can explain correction of the preoperative myopia [Table 2] and [Figure 3]a-d.{Figure 3}

There was no case needed conversion to standard penetrating keratoplasty, pupillary block glaucoma, graft rejection, and graft failure in this study.

 Discussion



In the past few years, DSAEK has gained favor with most corneal surgeons because microkeratome-assisted dissection of the donor cornea eliminates the complications associated with manual dissection while making surgery faster and simpler. [17],[18] Moreover, Descemet stripping in a closed AC environment, during recipient preparation, similar to capsulorrhexis which is a relatively safe maneuver and is unlikely to damage the quality of the overlying full-thickness stroma. [19]

In our initial experience in this case series, the visual acuity results and its speed of recovery were very promising. Nearly one half of the our patients achieved BCVA of 20/40 or better by 6 months after DSAEK which is in line with results given by Koenig et al. [12] However, it is considered to be slower in recovery if it is compared with other reports, e.g., Jorovoy M. (50% had BCVA of 20/40 or better after 6 weeks only). [19]

This slow visual recovery in this study can be attributed to the steep learning curve of the procedure. [20] With the adoption of any new surgical technique, there is an inevitable learning curve for the surgeon and an accompanying evolution in techniques.

In addition, all the cases were having advanced stromal edema with mild degree of anterior stromal scarring which limit the final visual results, but still better than the visual results of penetrating keratoplasty in psuedophakic bullous keratopathy and Fuchs dystrophy. [21] In our study, 100% of studied patients reached 20/50 or better at last follow-up visit.

DSAEK refractive surprises in phakic and pseudophakic were minimal.

This rapid predictable visual acuity recovery is important in such patients, many of whom have bilateral disease especially Fuchs dystrophy.

The regular keratometric astigmatism in this study (44.00 ± 1.9 diopter postoperatively) is comparable with results described in other studies, [12],[14] and this can be attributed to the small temporal sclerocorneal incision (5.00 mm). Moreover, unlike the suture induced irregular astigmatism and surface related problems expressed in penetrating keratoplasty. [21]

Concerns about final corneal thickness and visual results have been allayed by early clinical results. The postoperative corneal thickness measurements can reach up to 694 mm and can be optically clear and consistent with 20/40 visual acuity.

Corneal button holing during microkeratome passage mandate preserving another corneal donor graft during early cases.

Total graft dislocation in case (8) was observed at day 1 although the presence of 20% filled AC with air bubble gave impression that leaving air bubble in the AC at the end of the procedure, giving it subsidiary effect in fitting the posterior lamellar graft in its place. The risk of graft dislocation was recorded in multiple studies and ranged from 10 to 34.7%. [8],[11],[12] Multiple modifications in the DSAEK technique were suggested to reduce this complication, e.g., peripheral posterior stromal scraping [4] and presoaking the donor tissue. [22]

Measuring white to white of the recipient cornea is important before determining the trephination size of the donor cornea to avoid angle closure glaucoma secondary to crowding of the thick graft edge in the AC angle (like patient 10). Meniscus-shaped graft with thick peripheral edge is highlighted by schiempflug photo taken by Pentacam (Oculus Inc., Germany) [Figure 3]d, and this explain why we have to adjust the target biometry for −1.00 diopter. [14]

One of the drawbacks in this study is that it has small sample size with 1 year follow-up, but our aim of this cohort study is to express our initial experience during the learning curve. In addition, retrospective analysis without studying pre- and postoperative endothelial cell counts is one of the weak points in the study.

In conclusion, DSAEK is safe and effective procedure in patients with endothelial dysfunctions with encouraging surgical and visual outcomes.

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